next time you do some spirited driving, pop your throttle body off and run your finger inside the intake. If there is any oil on your finger you will benefit from having a catch can. On all the LSX engines, GM was never quite able to solve the issue of the PCV system sucking up oil vapor and sending it to the intake to be recycled back into the engine. Excessive oil in the combustion chamber can cause numerous problems, such as a continuous lean condition (the oil will make the o2 sensor think it is running rich and lean the mixture out).

What the catch can does, is it allows the oil vapor (that is in the air being vented) to condense and collect in the can instead of the intake manifold and combustion chambers.

I understand exactly! Crank case gases under high rpms force more crank case gases through the PCV (primary crank ventilation) through the intak to be recurculated and burnt if it can. This is even more prevalent in high mileage vehicles like mine where the compression rings may let more crank case gases through. That gas has certain amounts of oil in it that when it reaches the intake and cooler air and pockets will form actual oil puddles in the intake ( I spoke about my own having too much in the bottom in another thread) and then that can cause not only the problems that you spoke about with the sensors but also a problem when it gets to a certain level and the engine gulps a bit down. I have seen some real damage done from this (on a diesel engine) as oil does not compress well.

I did not know this was a concern with the LS1 and I will definately be getiing me a set up to bleed it off.

the easiest thing to do would be to convert to a LS2 or LS6 PCV system. They are an upgrade over the LS1 even without the additional venting in the LS2 block. It also removes a few hoses as well, cleaning up the engine bay some. I will take a pic of the LS2 system in my car and post it up.

The first time that I removed my intake, I noticed a small amount of oil inside it. I thought that was odd but I don't know what flows where so I didn't question it.

It is coming from the PCV system. It happens with all PCV systems with hard driving, but the LSX system scavenges crankcase pressure better than most which means more oil vapor being vented as well. GM discovered this, that is why they kept redesigning the PCV system.

Also as an engine gets more miles on it and the compression rings lose some of thier holding power more and more of the compression gases make it past them into the crank case. You have to vent that gas some where or you will eventually blow the oil seals and gaskets out or just force the oil past them. THis can also happen if the PCV valve gets gummed up and soesn't do what its supposed to.

A good PCV system will keep that to a minimum...

My intake has probably never came off and had 140,000 miles of driving on it with I'm sure some spirited driving here and there so I am hoping that is why I found what I believe to be too much oil in the bottom of the intake.

I also think its a little bit of a design flaw in the intake as when I am looking at it, it has a bend that runs down and would create a bole in the middle of the intake. Thats bad because thats what lets the intake pool the oil and eventually get that gulp that blows head gaskets or maybe even worse!

After this thread I think people will know more about the PCV system and crank case gases than they will care to know about.

Make sure that you blow the dirt back OUT of the radiator and condenser, not further in. Use air before water but make sure you don't use TOO MUCH PRESSURE. You can bend the fins if you do and that would really screw things up.

After cleaning, you need to get one of these:

"Marines - Making the other guy die for his country for over 200 years."

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